


Supergirl Flash Arrow DC Legends Crossover AU

by ijedi



Category: Arrow (TV 2012), DC's Legends of Tomorrow (TV) RPF, Supergirl (TV 2015), The Flash (TV 2014)
Genre: Alex Hank Lena James Winn Maggie going with Kara to Earth 1, F/F, F/M, but Maggie first will be jealous of Sara, end game sanvers, end game supercorp, who will have a crush on Alex
Language: English
Status: In-Progress
Published: 2017-01-06
Updated: 2017-05-27
Packaged: 2018-09-15 04:35:06
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 4,493
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9219242
Author URL: https://archiveofourown.org/users/ijedi/pseuds/ijedi
Summary: When Barry and Cisco visit Earth 38, they end up in Alex's apartment. Kara goes to help Barry, but Alex, Hank, Lena, James, Winn, and Maggie follow Kara. The large group of allies fight the Dominators.Since Barry and Cisco arrived before Alex and Maggie kissed, and before Alex and Maggie told they liked each other, Alex will not be sure that Maggie likes her, so she will be friendly with Sara Lance, and Maggie will be jealous.





	1. Leaving Earth 38

A blue breach opened into an apartment. Two young men exited it and looked around. “Are you sure it’s the right place, cause—” said Cisco, as both men immediately stopped talking, noticing that they were not the only people in the room. Two young women stood in the room talking, but they also stopped talking once they realized they were not alone.

“Who are you?” asked Alex Danvers. “How did you enter my apartment?”

“Should I charge them?” asked Maggie her friend. Alex shook her head.

“I repeat, who are you, and why have you arrived at my apartment?” Alex asked.

“Ok, you see, and this might sound strange, but we are here to meet up with a friend of mine. It’s a long story. We will leave, don’t worry, but do you by any chance know where Kara Danvers is?” Barry asked

Alex took a step forward. “Why do you want to contact my sister?” Alex asked.

“Oh, so you must be the Alex Kara told us about,” said Barry, extending his hand. “Hi, my name is Barry, and I met her for a few days when you were on the run a few months ago. I assume you resumed working at the DEO,” said Barry.

“Right, I remember Kara telling me about one Barry Allen whom she met while I was on the run. I remember she also told me that her former boss found you amusing,” said Alex.

“Good, I am glad we resolved the miscommunication. Look, can you tell me where Kara is, I really need to talk to her,” said Barry.

“I, I am not sure why you need to talk to her. I can call Kara I guess, and she can get here quickly,” said Alex.

“No need, I can run to meet her,” said Barry.

“And alter another timeline?” Cisco glared at his colleague.

“And how could Barry do that?” asked Alex.

“Oh common Alex, don’t you see, Barry is the Flash. I read in a paper somewhere that one can travel between places if enough speed is present, so since these two are here, I assume that Barry is the Flash, and they want to take Kara to help them,” said Maggie.

“I am sorry, and who are you?” Barry asked.

“Maggie Sawyer, Detective of NCPD,” said Maggie.

“Barry Allen, I am CSI, well former CSI of Central City Police Department,” said Barry.

“My name is Cisco Ramon, and I am his work college,” said Cisco.

“Why do you need Kara’s help?” asked Alex.

“Well, I,” said Barry, first looking at Alex, and then at Maggie.

“Alright, let’s first deal with the elephant in the room. Barry is the Flash, Kara is Supergirl, and Barry needs your sister’s help because of how powerful Kara is,” said Maggie.

“Maggie?” Alex asked.

“Look Danvers, I am a Detective, I detect. I saw Kara drink things only aliens can drink, and her glasses are not a really effective disguise. I cannot be the only one to realize this,” said Maggie.

Alex sighed. “Okay, I will call Kara, but she will not go with you before you explain the entire situation at the DEO. I think Hank might want to hear this, since if you need my sister’s help, Hank would need to also look at your situation,” said Alex.

Barry nodded. Alex called Kara’s cell. 

“Hey Kara, I need you to get to my apartment ASAP,” said Alex.

“Will be there in a minute,” Kara answered her phone and flew to her sister’s apartment. When Kara arrived, she climbed through the window to greet Alex, only then seeing Maggie, Barry, and Cisco.

“Detective Sawyer,” said Kara.

‘Hello Kara,” said Maggie. Kara immediately looked at Alex.

“Relax Kara, as I told Alex, I am a Detective, I detect,” said Maggie. “I realized you were Supergirl without anyone actually telling me this.”

“O, hey Barry,” said Kara, noticing her fellow friend superhero standing in the apartment.

“Hey, this is my friend Cisco Ramon,” said Barry

“More like work colleague,” said Cisco

“Anyway, remember I asked you a favor? I need your help,” said Barry.

“Sure. So what are we up against,” asked Kara.

“There is an alien invasion on our Earth, so I thought we could use our own friendly alien to help us repel the invasion of my Earth,” said Barry.

“Of course I will help,” said Kara

“No way,” said Alex.

“Alex!” Kara looked at Alex with her puppy look.

“No, I am not going to let you go there alone. What if something bad happens to you?” Alex said.

“Alex,” said Kara, “I have to go,” 

“What you have to do is first tell Hank about this. And if you want to go, I will go with you too,” said Alex.

“I,” said Kara.

“We appreciate all the help we can get,” said Cisco.

“Fine, let’s go,” said Kara. Alex smirked.

“DEO first, Kara,” said Alex, as Kara sighed. The group then quickly traveled to DEO with Kara carrying Alex, Maggie, and Cisco, while Barry ran on the ground following his flying friend.  
When they arrived, Kara saw that Hank was talking with someone.

“Hank, I need to talk to you,” said Kara, then seeing that Hank was talking to Lena Luthor.

“Greetings Supergirl,” said Lena. “Thank you for helping me defeat my mother.” She then looked back at Hank.

“We are grateful for your help and scientific contributions of what you learned from Cadmus,” said Hank.

“Hank, we have an urgent matter to discuss,” said Alex, when Hank noticed two new visitors in the room.

“Supergirl, do I need to make it even clearer that we have specific rules about having visitors at this facility,” asked Hank.

“Hey, my name is Barry Allen, I am the Flash,” said Barry

“Barry helped me defeat Livewire and Silver Banshee,” said Kara.

“OK, I will hear this. What do you need?” Hank asked.

“Aliens are attacking our Earth and we need help,” said Cisco.

“They call themselves the Dominators,” said Barry. Hank immediately froze in his place. 

“Agent Schott, call Director Lane and tell her that she has to arrive to this facility,” Hank then looked back at Barry, Cisco, and Kara. “This is a very grave threat, and I cannot let you go alone. I have some experience with these aliens. They are smart, travel in huge numbers, and don’t leave until they accomplish their objective,” 

“They left Krypton ages ago,” said Kara. “My father knew they scared me, so he assured me that Dominators would never bother Krypton,”

A realization occurred to Kara, and she face palmed. “Of course, dad created Medusa to repel any threat from these Dominators,” said Kara.

“Your father created the virus?” asked Lena. Kara nodded.

“So what is our plan?” asked Hank.

“We aren’t sure yet, but we planned to discuss it with Team Arrow and other friends how we will deal with these aliens. So far, they only seem to do intelligence gathering missions without full scale invasions,” said Barry.

“We will need to work on the plan,” said Hank. “Alright people, let’s move,”

“I need to get my gear and weapons,” said Alex

“Fine, we leave in five minutes,” said Hank.

Kara left to check on Mon El. After making sure he was doing fine, she noticed a familiar figure in the armory. He was standing next to Winn.

“Busted,” said Winn.

“I did not know that you helped this Guardian vigilante,” said Kara, walking towards two men, and smacking Winn lightly.

“Ouch, ouch,” said Winn

“And you, why are you doing this?” Kara tried to check Guardian’s identity, but the lead mask concealed his face.

“I am a friend. I want to help,” said James.

Kara sighed. “Normally I would be furious with you two, but since Alex, Hank, and I would be leaving to help Barry at his Earth, you two can stay and protect National City,”

“You are going to help Barry?” asked the two men simultaneously.

“How do you know who he is?” Kara raised her eyebrow.

“Well, you see, I told the Guardian about other Superheroes and Vigilantes from this Earth and other Earths, so he knows,” said Winn

“Right,” confirmed James, still concealing his face.

“Makes sense,” said Kara. 

“But, since you will be leaving, I want to come help. You might be in a situation where you would need someone skilled but not super powered,” said Guardian.

“But this city,” said Kara

“This city has Mon El, since he is definitely not going but can likely help in case an emergency arises,” said Winn.

Kara put a hand on her face. “Fine, meet me in the meeting room, where we will be going to the other Earth,” said Kara, taking away her hand from her face, and walking away.

“That was close,” said James

“Yup. We will have to tell Kara sooner or later,” said Winn.

“Agreed, but not yet,” said James.

When Kara returned, she noticed that Lena was talking to Barry and Cisco. “Hey Supergirl, I never knew you had such smart friends. Miss Luthor just told us about some of the inventions she created,” Cisco said.

“Yeah, and your plan to defeat your evil mother worked perfect,” said Barry.

“Supergirl, hi, I was talking to your friends over here, and I was thinking of also helping defeat these aliens. I still have another prototype of alien detection device, so theoretically I could create another device to detect their presence at a specified location. I also have an extensive knowledge in Engineering, which I can use to help,” said Lena.

“We would have the greatest geek squad across all the teams,” said Cisco. “And I thought we would only have Caitlin, Felicity, and I, and now we would have Lena,”

“Hey, I am a CSI,” said Barry. “I also technically count,”

“Someone was talking about geeks?” asked Alex, approaching the group.

“While most heroes on our earth can kick ass, we have a few geeks and nerds who are the brain power,” said Cisco.

“Well, I have a PhD in Alien Physiology, and my main focus is Bioengineering,” said Alex.

A few minutes later, when everyone assembled, Cisco prepared to activate the portal to Earth 1. Hank was surprised to see that Winn, Guardian, Lena, and Maggie also decided to join. Nevertheless, he didn’t argue against the inclusion of the increased roaster of people since he knew that the higher number of people would improve the chances to defeat Dominators.

“Alright, listen up. I know you are all eager to help, but the mission we are going will be difficult and dangerous. I would understand if anyone wished to back off at this point, since the Dominators are dangerous,” said Hank, but nobody left. 

“Good, so it’s time to go,” said Hank. Cisco opened the breach, and the group quickly transported to the other Earth, leaving DEO behind. Hank hoped that Director Lucy Lane would be able to assemble a competent temporary staff during this mission to protect National City while he would be away with Alex and Kara.

The group arrived in a storehouse, where they saw many people standing there already. “What the hell Barry, I thought you would be bringing an alien, and you brought so many people,” said Oliver disapprovingly.

“Circumstances changed, but now we have even more allies to help defeat the Dominators,” said Barry.

“Can we take a break, cause I really need to get some food before I can do anything, since I haven’t planned to run as much while carrying more people than I thought I would be,” said Barry.  
“Fine. Let’s recess, but I want you all to be ready ASAP in fifteen,” said Oliver.

The group dispersed. Cisco told Caitlin and Felicity about Lena and Winn and their intellectual interests, so the nerds of Earth One approached her and the five talked about science. 

James walked towards Oliver, wanting to ask several questions about being a vigilante without superpowers, since he assumed Oliver also did not have powers. Kara joined Barry in eating enormous quantities of food, while Hank just sat on a chair, thinking how they would defeat the alien invasion. 

Alex and Maggie sat at a table, with Alex finding a bottle of Whiskey. They saw that a blonde woman dressed in a white costume approached them. “Hey, my name is Sara Lance,” said Sara.

“Alex Danvers”

“Maggie Sawyer”

Sara ignored Maggie and looked at Alex. “You look hot,” smirked Sara, leaving stunned Alex, who was unsure how to react.

“Thanks, I guess,” said Alex.

“After it’s all over, I can show you some moves,” winked Sara, leaving the two women. Alex hasn’t noticed that Maggie kept glaring at Sara Lance, apparently not liking her.

A/N: I decided to write a crossover as to how I think it should have been with Supergirl cast being present in the crossover as well. Barry and Cisco arrived before Alex and Maggie kissed, and before Alex and Maggie told they liked each other.


	2. Introductions

**Summary for the Chapter:**

> The four teams introduce themselves, Alex and Oliver spar to see who is the better fighter, and Sara expresses interest in spending time with Alex.

After the recess was over, the four teams decided to introduce themselves to their new allies, since especially Kara and her friends did not know anyone except Barry and Cisco on Earth One. 

“I guess now we should do the introductions,” said Kara

“That would be my preference,” agreed Oliver, since he always preferred to know just who he was working with.

“Alright, so I guess I will start. My name is Kara Zor El, or Kara Danvers, and I am known as Supergirl on my Earth,” said Kara, only then realizing that two one person from her Earth did not actually know her secret identity.

“Kara?” Lena asked, looking at her best friend. Kara blushed. 

“And this is my team. Agent Alex Danvers is my sister, who works for the DEO, where we defend the Earth against alien threats. J’ohn is the Martian Manhunter,” said Kara, and then continued to tell who was who on her Earth.

“What are you powers?” asked Felicity

Supergirl smiled and flew in the air, and then shot lasers from her eyes. She then landed next to everyone. “I also have super strength, super durability, super breath,” said Kara.

Barry decided to introduce his teammates. “Most of you know me as the Flash. These are my friends and family,” said Barry, and like Kara introduced his friends and family to others.

“So your entire team consists of meta humans? That’s awesome,” said Winn.

“Well, not the entire team. Iris, Joe, and HR are regular people,” replied Barry.

Winn nodded. “So what are your powers? You look like the Flash?” Winn asked Wally.

“Well, I am Kid Flash, and have the same powers as Barry does,” said Wally

“And I can make vibes, to show vibrational energy at others, open breaches that function like teleporters, and look at other places,” said Cisco.

“Cool,”

“Barry, you said that only Iris, Joe, and HR don’t have powers. What about Caitlin,” asked Amaya.

“Well, Caitlin has ice powers,” said Barry, smiling, only then realizing that he revealed his friend’s secret. “Caitlin, I am so sorry,” 

“It’s fine,” said Caitlin. She smiled, but when Oliver began to introduce his team, Caitlin walked away and stood silently in the corner, upset that everyone now knew of her powers.

“Wait, you are all vigilantes and you actually killed people?” Maggie asked Oliver.

“I,” Oliver was not sure how to respond.

“Do you realize that I am a police officer, a Detective?” Maggie asked.

“Don’t worry Detective, he is a good boy. Now I like to burn things,” smiled Mick Rory, looking at Maggie.

“Is he joking?” Maggie asked Barry, who stood next to her.

“Well, Mick was a criminal before,” replied Barry.

Once Oliver introduced his team, Sara began to introduce the Legends. During the introduction, Captain Lance approached Maggie.

“Detective Sawyer? My name is Quintin Lance, and I am former Detective and Captain of Star City police. I know you might feel uneasy working with some of these people, especially Mick Rory out there, but I know that at least you can trust Team Arrow, and you can trust the judgment of my daughter. Now, she does not always make the right decisions, but I trust my little canary,” said Quintin.

After Sara finished introducing her team, Kara, Oliver, and Barry left the others and decided to speak between themselves, while the remaining members of the super team up intermingled, with the tech savvy people talking to one another, Alex and James talking to Oliver’s team, Maggie talking to Joe, Iris, and Quintin. Wally talked to the New Recruits, who were then joined by the Legends and HR, who took some notes on the adventures, wanting to write a book based on them.

“So, what’s the plan?” Barry asked Oliver and Kara

“Barry, you told me that you would bring one ally, but now we have to coordinate four teams and very many people in defending the earth against the alien invasion,” said Oliver

“I thought it would be beneficial for us to have as many allies as we could. Besides, Kara’s sister was adamant on following Kara, and the others just followed,” said Barry.

“My friends will help,” said Kara

“I appreciate the enthusiasm, but I am worried that your friends might be put in danger especially if they don’t have much intensive training, although your sister, Winn, and Lena can help our resident geniuses. I am not sure how well trained James or Maggie are, but,” said Oliver.

“Hold on one second, here Mister Arrow,” said Kara, “But James and Maggie are fully capable in defending themselves. From where I come from, we fight aliens all the time, and James and Maggie already have shown many times to be able to hold their own in helping. And my sister is the best DEO agent, who had extensive training and I bet she can defeat you in a fight,” said Kara

“Is it wise to bet this? Oliver was stranded on the island for five years and learned how to fight from multiple people,” said Barry

“Three, I was on the island for three years,” said Oliver

“And my sister had years of training and she fights aliens on the regular basis. She can take a mere human, especially someone as cocky as you,” said Kara.

Kara and Oliver looked at one another. Mick approached them, since he noticed the disagreement. “Is Supergirl going to fight the Green Arrow? I want to watch this,” said Mick.

“No, we just had a disagreement,” said Oliver

“Don’t worry, Oliver and Kara are just arguing over whether Alex can bear Oliver in a fight,” said Barry, and then smiled cheekily at Oliver, who was not amused.

“Oh, that’s great. Listen up people, make space for the fight of the century, where Alex Danvers would be fighting Oliver Queen,” said Mick Rory loudly. Everyone immediately looked at him, and then at Alex and Oliver.

“No,” said Oliver.

“Common boss, everyone needs to see you in action,” said Rick.

“I don’t think we should fight,” said Alex.

“Alex, he told me that he thinks you, James, and Maggie, but especially you Alex, cannot fight!” Kara said.

Oliver and Alex looked at one another. “Fine, we will fight. But no lethal moves,” said Alex.

“Agreed,” said Oliver.

Alex and Oliver stepped in the middle of the room, while the others took a few steps back, providing the room for the two fighters.

Alex and Oliver charged at one another and began exchanging hits. Oliver once hit Alex, throwing her on the ground, but the Agent jumped back on the ground. Alex then evaded another hit, and kicked Oliver in the stomach, sending him on the ground. Oliver quickly stood up and the fight continued.

“Wow, that’s impressive,” said Thea

“Yeah, my sister can fight and your brother was wrong for underestimating her,” said Kara.

“I know, my brother can be dumb sometimes,” said Thea. Alex and Oliver continued to fight.

“I feel bad,” said Curtis

“Yeah. I can fight but they are fighting on a different level,” said Rick.

The fight continued, but neither opponent was ready to give up. Both Alex and Oliver were sweating, but they still seemed to have a lot of energy left in them.

Kara kept observing the fight, and then looked at Maggie, noticing that the police officer was blushing. Kara then approached Maggie. “Hey Maggie, I didn’t know you enjoyed watching fights,” said Kara.

“Not really, but don’t you see how badass your sister is, Kara? Damn, Agent Hot Damnvers,” said Maggie.

“Oh, I see, you like to play with my sister’s heart, don’t you, Detective Sawyer? Well, let me tell you that if you cause my sister to cry like you did in the past, nobody will find your body. In fact, I might ask someone here to keep you on this Earth,” smiled Kara.

“What happened to Sunny Danvers?” Maggie asked.

“What happened? Maggie Sawyer happened, and you should know that hurting my family, especially my sister makes me angry,” said Kara

“That’s so unfair, I had reasons when I said Alex and I should not be together,” said Maggie but Kara left her, not wanting to listen to the Detective who broke her sister’s heart.

Ten minutes later, and Alex and Oliver were still fighting one another. “You are good,” said Oliver.

“You are not so bad yourself,” said Alex, as they kept sparring. 

“You know what? Let’s call this a draw, it’s obvious you two are equally matched,” said Sara. Alex and Oliver looked at one another and agreed.

Kara instantly flew to Oliver and her sister. “See? My sister is a very good fighter,” said Kara.

“Fine. I was wrong to judge your friends, since I don’t know many people who are very good fighters, but meta humans are more common,” said Oliver.

“I think we should have others spar as well,” suggested Alex.

“That would be a good idea, but I don’t want to put metas against regular humans yet,” said Oliver.

“I was thinking more of a non- super powered sparring at first, while the others rest, and then we have a proper sparring session,” said Alex.

“I agree,” said Oliver.

“Hey guys, why don’t you also fight and help one another prepare for fighting against Dominators,” said Kara. 

People agreed and began fighting, with Maggie insisting to fight with Sara. While the others were experienced fighters, Sara was almost if not as good as Oliver in fighting, while Maggie was more like the others on Team Arrow, but not quite on Sara’s level. Despite this, and despite being thrown on the floor many times, she persisted, and fought Sara with all her strength.

James Olsen and John Diggle noticed that Maggie and Sara fought more intensively than the others. “Hey Maggie, it’s OK, this is just a practice session, we don’t need to fight this hard,” said James.

“Yes, and I would also recommend to preserve our strength for the upcoming battles,” said John Diggle, but Maggie ignored them and continued fighting Sara, who actually wasn’t even tired from the fight, since unlike every other fight, this one was somewhat one sided.

After landing on the ground one more time, Maggie took a deep breath and slowly stood up. “You know what, I give up. I will see you all later, I need to rest,” said Maggie, walking to a nearby table to catch a breath. She felt like shit after Kara’s disapproval of her friendship with her sister, and after the beating she received from Sara.

While people kept sparring, and the others observed the fights, Alex approached Catilin, since she noticed that Caitlin was still standing in the corner. “Hey,” said Alex.

“Don’t come close to me, I cannot control my powers yet, and I fear that if I use my powers, I will turn evil,” said Caitlin.

“Maybe I can help, I have a PhD in bioengineering, and I could help find a way for you to get a hold of your powers, or possibly curing you of those powers if you want,” said Alex.

“You would do that?” Caitlin asked.

“Sure. Besides, it would be great for me to talk to other biology scientists, since I mostly fight bad guys,” said Alex. Caitlin smiled and decided to rejoin her friends.

“Wow, that was some great fighting, I approve,” said Sara, approaching Alex.

“Recently you told me that I look hot. Are you sure? Cause recently I came out to a friend of mine, and then she rejected my advances since she told me that I was fresh of the boat,” said Alex.

“What nonsense, you look hot, Agent Danvers. If you want, I can show you some moves,” said Sara, stepping closer to Alex, and bring their lips closer.

“Not here, let’s go to somewhere more private,” said Alex.

“Agreed,” said Sara, and the two women walked to a small room in the building.

A few minutes later, Kara began to wonder where her sister went. “Alex? Alex, where are you?” Kara looked around but could not find her sister. She then approached Maggie. “Have you seen Alex?”

“I thought you did not want to talk to me,” said Maggie.

“Yes, but Alex is still your friend, and I thought you knew where she is,” said Kara.

“I don’t, but I can help to search for her,” said Maggie. The two women then began searching the building, looking in different rooms, before finally approaching the last door and opening it, only to find Alex and Sara kissing passionately, with Sara’s hands under Alex’s shirt.

“I,” Kara took a step back and instantly covered her eyes. 

“What the hell Kara! I just wanted some alone time with Sara. Maggie? What are you doing here,” asked Alex.

Kara was still immobile, unable to move, and trying to forget what she just have seen. Maggie was the first one to move. “You know what, I forgot that I needed to speak with Joe and Quintin,” said Maggie, quickly leaving the room.

Sara took away her hands from underneath of Alex’s shirt and the two dressed properly. “You can look now, Kara,” said Alex, and Kara looked at her sister.

“I can’t believe I’ve seen you doing these things! First Winn with Silver Banshee, then Mon El with Miss Tessmacher, and now you with this time travelling ninja? Rao, why do I keep walking on people kissing?” Kara paused.

“Let’s get back to the others,” suggested Sara, and the Danvers sisters agreed. The three women exited the room.

A/N: I wanted to write some Sanvers angst, but don’t worry, Sanvers is endgame! And Alex and Maggie will begin dating but since the events of this fic began before Alex and Maggie were able to kiss after the events of “Medusa,” Alex and Maggie are not yet girlfriends.


End file.
